This invention is related to an improved method of preparing soap dispersions in textile fluids for use as a textile fiber finish for synthetic fibers, particularly magnesium stearate dispersions in silicone fluids for use on Spandex(copyright) and related fibers.
Spandex(copyright) type fibers have been in existence for many years, and many improvements have been made to these fibers, their processing and their use. In U.S. Pat. No. 3,039,895 (Jun. 19, 1962) there is described a fiber finish consisting of a textile oil containing finely divided soap particles. As the ""895 patent defines a textile oil, it seeks to cover a broad range of oils including mineral oils and silicone oils. The ""895 patent also describes a broad range of soaps including those requiring supply as finely divided powders.
Subsequent patents and the literature have added to the textile oil field such enhancements as the addition of an amyl (pentyl) containing siloxane as disclosed in U.S. Pat. No. 3,296,063 (Jan. 3, 1967). Other examples include U.S. Pat. No. 3,896,032 (Jul. 22, 1975), U.S. Pat. No. 4,105,567 (Aug. 8, 1978), and U.S. Pat. No. 4,217,228 (Aug. 12, 1980). Each of these latter patents are directed to new and improved versions of what the ""895 patent referred to as the textile oil.
Some other examples of improvements to these dispersion compositions are shown in U.S. Pat. No. 5,135,575 (Aug. 4, 1992) where there is disclosed a method of producing more stable dispersions of particulates including magnesium stearate in both organic and silicone based fluids by adding an alcohol. In U.S. Pat. No. 5,595,675 (Jan. 21, 1997) there is described a fiber treatment composition utilizing a silicone resin additive for stabilizing the dispersion.
Thus, it can be seen that many combinations of oils and soaps exist. Surprisingly, however, this technology is part of a growing market for these fiber finishes, and yet there has not been anything in the public domain concerning the processing of the soap in oil dispersions first disclosed in the ""895 patent. This appears to indicate that those producing these materials are using what might be considered the standard dispersion technology. For example, in Perry""s Chemical Engineers Handbook, Fifth Edition, on Pages 8-25, several examples of typical mills are shown which are adapted for preparing these types of soap in oil dispersions.
An additional example but in another industrial application for a method similar to a two step masterbatching process for producing these types of textile finishes can be found in U.S. Pat. No. 3,951,849 (Apr. 20, 1976), where there is disclosed a paste production method in which there is first premixed a solid material, a vehicle, and a deagglomerating agent, and the premix is then passed through a colloid mill.
Another example is U.S. Pat. No. 4,416,790 (Nov. 22, 1983) which discloses a paste like damping medium for damping mechanical and/or acoustical vibrations, based on a silicone oil, polyglycol, mineral oil, and or a thermally stable aliphatic or aromatic carboxylic acid ester, a finely divided solid material, an agent for reducing the surface tension, and an agent for increasing the intrinsic viscosity.
It can only be speculated about how those in this field prepare these kinds of dispersions, but likely they produce the oil in soap dispersions either in small processing units located at several sites in various countries around the world, or they produce the oil in soap dispersions in one or a few large processing units, and subsequently ship the dispersions around the world and into the countries where the materials are used to treat fibers. Both approaches, however, possess inherent economic disadvantages in global markets. The present invention provides a novel mode of improvement.
Thus, according to the present invention, a single masterbatch or concentrate of soap in oil is prepared in one site globally. Masterbatches from this large production site are then shipped to various sites close to the point where final fibers are produced, and the masterbatches are converted into the final fiber treatment products desired. This allows producers to make one masterbatch composition in a large scale facility, and then to convert it to any of a family of final products, in much smaller, simpler, lower cost, production facilities in various places around the world.
The essence of this invention, therefore, is preparing a masterbatch or concentrate in a specialized process which can be subsequently shipped anywhere in the world, and diluted into the final product in very simple mixers using no specialized size reduction equipment. In fact, it was unexpected and surprising that by producing a masterbatch concentrate, it is possible to complete the solid size reduction and deagglomeration required in one process, and then to move the masterbatch to another process where the final dilution with textile oils is completed in very inexpensive equipment and without the need for particle size reduction equipment.
The present invention has other advantages over production methods used in the prior art in that one is enabled to ship a masterbatch to various countries in the world, and possibly along with the remaining textile oil diluents. When importing such materials into a country, the masterbatched compositions would be subject to lower tariff duty rates than would the comparable finished products, because final dilution would be performed inside the local country. In contrast, if one prepares the final soap in oil dispersion in a large centralized process, the corresponding tariff duty rates would be much higher when shipping the dispersion into other countries because there would be no further processing carried out on finishing the goods in the country of destination. While the shipping costs would be comparable, the tariff import duties on the finished fluid would be lower according to the concept of the present invention, i.e., masterbatching.
The masterbatch technique of this invention has other advantage over a centralized final product production mode because masterbatched compositions can be shipped to any final production point and then converted into any number of unique localized formulations. It can even be sold to custom formulators who could then add specialized dilution additives which enable the sale of the products to the local end users. Embodiments such as this allow the masterbatch process to operate at a high throughput rate to produce one intermediate, which is then easily converted into a multiple of final products using inexpensive processing equipment.
In addition, the masterbatch technique according to the present invention has major advantages over global production strategies, i.e., where many sites around the world convert virgin non-masterbatched raw materials directly into their final products. Thus, sites around the world need only the simplest of blending equipment and practically no powder handling equipment. However, the processing of non-masterbatched raw materials at each site requires that each site have both the powder handling capability, as well as sophisticated mixing and grinding systems to reduce the particle size of the solid soap particles in the textile oil. With the masterbatch method producers are enabled to utilize a single high throughput process in the world and numerous inexpensive and simple dilutions systems around the world. This is less costly overall than the installation of a number of small grinding and mixing systems globally.
Since textile fluids are often produced in a small number of high capacity processing facilities around the world, it is preferable that the masterbatch process should be located near the source of the main textile oil. In the most preferred embodiment, the masterbatch process would be located near the silicone fluid production site, therefore, allowing the silicone fluid to be converted into a masterbatch practically directly from the silicone fluid process, and without the need of any further packaging, storage or shipping.
This invention is directed to a method of preparing dispersions of solid salts of fatty acids in low polarity liquids. A concentrated mixture of at least 50 percent of the solid salts of the fatty acids in a low polarity liquid is subjected to high shearing forces until the average particle size of the solid salts of the fatty acids is less than 3 micron. The dispersion may then be immediately, or at any later time, diluted with more of the low polarity liquid to a lower concentration of about 1 to 50 percent of the solid salts of the fatty acids.
In particular, the concentration of the solid salt of the fatty acid in the concentrated mixture is preferably at least 60 percent during the application of the high shearing forces, which is carried out at near ambient temperature and atmospheric pressure. The solid salt of the fatty acid is most preferably magnesium stearate, while the low polarity liquid is a polydimethylsiloxane fluid having a viscosity of less than about 100 centistoke (mm2/s). The duration of the high shearing forces used in the process is less than one hour, and preferably less than about 30 minutes. These and other features of the invention will become apparent from a consideration of the detailed description.